Recently, computer printing leaped off the two-dimensional (2D) page into the three-dimensional (3D) world. Conventional 2D printing involves placing tiny grey or colored dots onto a 2D array on a sheet of paper to form the pixels of an image, such as a colorful picture or black-and-white text. In contrast, 3D printing uses a physical material to form volumetric pixels, or “voxels,” to build a 3D object. Generally, 3D printers print layers of an object, one over the other, to systematically place voxels into a 3D array to build the 3D object. 3D printing may be used for a variety of applications, including manufacturing, medical field, food industry, and so forth.
3D printing is supported by a variety of types of 3D printing technologies, including additive and subtractive types of manufacturing. Subtractive manufacturing can be used with 3D printing by melting or otherwise removing portions of a material to reveal the 3D-printed object, e.g., milling. An additive manufacturing process uses some material to create a 3D object by growing or combining the material to build the 3D object.
One example of additive manufacturing process is granule-based 3D printing, which is also referred to as binder jetting, powder-bed printing, 3D inkjet printing, and so forth. With granule-based 3D printing, a granular material, such as a powder, is spread in a thin layer across a printer bed of a 3D printer. A binding agent is then selectively applied to areas of the granule layer that are to be bound together for the current layer of the 3D object being printed. The binding agent acts as an adhesive to glue, melt, weld, or otherwise bind together individual granules of a current granule layer. To apply the binding agent, a print head mechanism of the 3D printer ejects or extrudes the binding agent into areas where the granule material is to be merged together to form a base, wall, support member, decorative element, or other part of the 3D object being printed.
Granule-based 3D printing offers a number of advantages over competing 3D printing technologies. For example, the resulting 3D objects can be formed from many different materials because the granules can be produced from many different substances. Examples of substances that can be used to produce granules include ceramic, metal, sand, and plastic. As an additional advantage, 3D objects can be built using multiple different colors with a granular-based printing technique. To achieve multi-color 3D prints, different pigments are combined with the binding agent before or during the application of the binding agent to the granules. For instance, cyan, magenta, yellow, black, or white pigments can be mixed to provide a full spectrum of colors.
Conventional granule-based 3D printing techniques, however, encounter numerous challenges in comparison to other 3D printing technologies. For example, conventional techniques rely on a user to manually locate a 3D objected printed in a granule-based printer bed, which may cause breakage. At the end of each printing run with a granular-based 3D printer, for instance, the printed 3D object is hidden by layers and volumes of the granules that are used as the printing material. Because the 3D object is buried by these layers and volumes granules, unused granules are separated from the 3D objects in a printer bed. Conventional approaches to separate the 3D objects from the unused granules, however, include long and tedious extraction processes that can result in damage to the printed 3D objects, e.g., through use of manual tools and “guess work” to locate the 3D object in the printer bed. Consequently, conventional techniques used to locate a 3D object may damage the object.